The wonderful and free Tofu (550 Kb) has been updated with some bugfixes. If you ever read chunks of writing on screen then you definitely need Tofu.
In Tofu, text is arranged in columns, and each column is only as high as your window. So lines are nice and narrow, they don’t move about vertically, plus your text is now in easy-to-digest chunks. You just scroll from column to column horizontally, and feel more in control.
Tofu also includes some other useful features to make reading easier for you. You can jump to any point in your text by simply typing some letters near it (without choosing any command first). There’s a “View In Columns” service so you can, for example, grab some text from a web page. And it lets you use your voice to navigate text, so you can literally sit back and read.